Various caches for incremental compilation.

dart/sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 class NativeEmitter {
 
-  CodeEmitterTask emitter;
+  final Map<Element, ClassBuilder> cachedBuilders;
+
+  final CodeEmitterTask emitter;
   CodeBuffer nativeBuffer;
 
   // Native classes found in the application.
   Set<ClassElement> nativeClasses = new Set<ClassElement>();
 
   // Caches the native subtypes of a native class.
   Map<ClassElement, List<ClassElement>> subtypes;
 
   // Caches the direct native subtypes of a native class.
   Map<ClassElement, List<ClassElement>> directSubtypes;
 
   // Caches the methods that have a native body.
   Set<FunctionElement> nativeMethods;
 
   // Do we need the native emitter to take care of handling
   // noSuchMethod for us? This flag is set to true in the emitter if
   // it finds any native class that needs noSuchMethod handling.
   bool handleNoSuchMethod = false;
 
-  NativeEmitter(this.emitter)
-      : subtypes = new Map<ClassElement, List<ClassElement>>(),
+  NativeEmitter(CodeEmitterTask emitter)
+      : this.emitter = emitter,
+        subtypes = new Map<ClassElement, List<ClassElement>>(),
         directSubtypes = new Map<ClassElement, List<ClassElement>>(),
         nativeMethods = new Set<FunctionElement>(),
-        nativeBuffer = new CodeBuffer();
+        nativeBuffer = new CodeBuffer(),
+        cachedBuilders = emitter.compiler.cacheStrategy.newMap();
 
   Compiler get compiler => emitter.compiler;
   JavaScriptBackend get backend => compiler.backend;
 
   String get _ => emitter.space;
   String get n => emitter.n;
   String get N => emitter.N;
 
   jsAst.Expression get defPropFunction {
     Element element = compiler.findHelper('defineProperty');
@@ skipping 228 matching lines @@
       if (nativeAncestor != null) {
         map
           .putIfAbsent(nativeAncestor, () => <ClassElement>[])
           .add(classElement);
       }
     }
     return map;
   }
 
   ClassBuilder generateNativeClass(ClassElement classElement) {
+    ClassBuilder builder;
+    if (compiler.hasIncrementalSupport) {
+      builder = cachedBuilders[classElement];
+      if (builder != null) return builder;
+      builder = new ClassBuilder(backend.namer);
+      cachedBuilders[classElement] = builder;
+    } else {
+      builder = new ClassBuilder(backend.namer);
+    }
+
     // TODO(sra): Issue #13731- this is commented out as part of custom element
     // constructor work.
     //assert(!classElement.hasBackendMembers);
     nativeClasses.add(classElement);
 
     ClassElement superclass = classElement.superclass;
     assert(superclass != null);
     // Fix superclass.  TODO(sra): make native classes inherit from Interceptor.
     assert(superclass != compiler.objectClass);
     if (superclass == compiler.objectClass) {
       superclass = backend.jsInterceptorClass;
     }
 
     String superName = backend.namer.getNameOfClass(superclass);
 
-    ClassBuilder builder = new ClassBuilder(backend.namer);
     emitter.classEmitter.emitClassConstructor(classElement, builder);
     bool hasFields = emitter.classEmitter.emitFields(
         classElement, builder, superName, classIsNative: true);
     int propertyCount = builder.properties.length;
     emitter.classEmitter.emitClassGettersSetters(classElement, builder);
     emitter.classEmitter.emitInstanceMembers(classElement, builder);
     emitter.typeTestEmitter.emitIsTests(classElement, builder);
 
     if (!hasFields &&
         builder.properties.length == propertyCount &&
@@ skipping 150 matching lines @@
       if (emitter.compiler.enableMinification) targetBuffer.add(';');
       targetBuffer.add(jsAst.prettyPrint(
           new jsAst.ExpressionStatement(init), compiler));
       targetBuffer.add('\n');
     }
 
     targetBuffer.add(nativeBuffer);
     targetBuffer.add('\n');
   }
 }